Exporting a DWG from Revit to be used in VIZ is one of the better options accept for VIZ modeling. The REVIT>DWG>VIZ has so much control ovr the process which you wont find anywhere. You CAN'T just export to DWG and expect it work for you.
In Revit there is an EXPORT setting dialogue box that lets you pick and choose a color ID for each and every part of an object, so for example a door would have different IDs for its frame, swing, glass, hardware... for ease of matterial applying in VIZ through multi/sub-object mat type. Same goes with every objectlike stairs, railings, windows... You can save and load different DWG exporting standarts depending on which program you intend to export to and the way it handles.
Revit exporting is VIEW SPECIFIC, so you have to be in a 3D view when you actually export.
Inside VIZ, use file link, and you have to make sure "Unify Normals" Option is uncheck.
As with every program, some things would be smarter to model directly in VIZ for better UVW. Same goes with for furnitures, trees and other small stuff that are better to be inserted in VIZ from a library.